Diversity and classification of marine benthic algae
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Chlorophyllian photosynthesis is responible of almost all primary production at global
level and represents the most fundamental process for the support and maintenance
of life on our planet. Organisms performing photosynthesis occur in every habitat in
which sunlight is available. Whereas vascular plants are largely responsible of
photosynthesis on land, in aquatic habitats this process is mainly perfomed by the
wide and heterogeneous complex of organisms called algae.
In the widest sense, algae are defined as oxygenic photosynthesizers other than
embryophyte land plants (Cavalier-Smith, 2007). In recent years our knowledge of
these organisms has greatly advanced, thanks to new types of data (mainly electron
microscopy observations and DNA sequence data). Based on these data, we know
now that algae represent an artificial and unnatural agglomeration of very different
organisms, sharing the only common characteristic of living in aquatic habitats. Algae
living in the sea are typically subdivided in plankton (the complex of microscopic
algae not visible with unaided eye, which live floating in the water) and benthos (the
collectivity of the algae that live attached to the sea bottom).
The algae that form the benthos are plant-like organisms, very diverse and very
different in size, shape and colour; they are are typically designated with the term
seaweeds. Despite of the undeserved negative connotation associated with such a
name, seaweeds play a fundamental role marine ecosystems, where they have a
multitude of beneficial effects. Although unrecognized, they also have an important
part in our everyday life. Substances extracted from seaweeds occur in toothpastes,
shampoos, cosmetics, drugs, soups, ice creams, soft drinks, beer, jellies,
marmelades, salad dressings, chewing gums and many other products of large use.
In China, Korea and Japan some species of seaweeds are among the most popular
foods, and for this reason they have been farmed for many centuries.
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